[boost] [serialization] Boost.DateTime tests failing

I see that a few tests of Boost.DateTime (see [1] for instance) are failing because Boost.Serialization fails to complile. It seems like revision 62546 caused this. Robert, will you take a look at it? [1] <http://www.boost.org/development/tests/trunk/developer/Sandia-darwin-4-0-1-date_time-darwin-4-0-1-testgreg_serialize-variants_.html>